Fuel supply means for internal-combustion engines



Aug. 15, 1944. A. c. DURDIN, JR 2,355,713

FUEL SUPPLY MEANS FOR INTERNAL-COMBUSTION ENGINES Filed June 24, 1940 5 Sheets-Sheet l 3 y/gwmw @W {1M Aug. 15, 1944. Q R JR 2,355,713

FUEL SUPPLY MEANS FOR INTERNAL-COMBUSTION ENG INES Filed June 24. 1940 5 Sheets$hee t 2 82' jzadezo Z01? Ja Sim C ficard :51) J2: 1

Aug. 151944.

A. C. DURDIN, JR

FUEL SUPPLY MEANS FOR INTERNAL-COMBUSTION ENGINES Filed June 24, 1940 5 Sheets-Sheet 5 Aug. 15, 1944. c; DURDIN JR 2,355,713

FUEL SUPPLY MEANS FOR INTERNAL-COMBUSTION ENGINES Filed June 24. 1940 5 Sheets-Sheet 4 wpn 1944' A. c. DURDIN, JR 2355;713-

FUEL SUPPLY MEANS FOR INTERNAL-COMBUSTION ENGINES FiledJune 24. 1940 s Sheets-Sheet s ifa nets s 2,355,113

cosmosrron ENGINES Augustus C. Durdin, .lr., Lincolnwood, BL, 181

I or of twenty-four per cent-to 'Amstus 0.

Durdin III, Rockford ,lil andtwenty-fourper Q 7 71 oenttoiewlsflrnurdimltirminxhamdla. Application a ette, 1m, n crises 7 i '11 chime, (cuss-fun) The present invention" relates to fuel supply means for internal. combustion engines andhas for its primary object the provision of anew and improved fuel supply means making prac-' bustion engines comprising a supercharier and means'for supplying a ticable theuse of inexpensive high flash point pletevaporization' of the fuel.

v fuels in internal, combustion engines of various A further more speciilcobiectoi the invention types, and especially in airplane engine's. Y residesin providina a system of that!" M Fuels having a hi h flash point such, for inmentioned with fuel supply means comprisinl a stance. as 100 F., have not heretofore been pracpeir of Venturi tubes. eo'nnectediin the ticable for operation'of internal combustion'en 1o outlet of one-of which iseonnected to the Mr ginesbecaus'e' or the lack of satisfactory means tion side ofthe superchargerand m inlet of for vaporizing them. Fuels of this nature have which is connected to atmosphere. and theloutmany advantages over-highly volatilefuels maklet of the other of which is connected to the in: them hikhly desirable. For instance, they 1 throat of theflrstandjthe inlet of which II 00 cfllmot be i nited by incendiary bullets, they do nected to the discli'arze side of the 9 11 1 1. not burn ii suddenly released over the wreckage thereby W and "10mm? of an airplane, and their cost is but a fraction vaporized supply of the fuel for theenzinen a of that of the hi'ghl'yfvolatile fuels now used. A further object or the invention resides in the Fuel injection devices, sucnasVentur-i tubes, t utilization of heat generated by and obtained which are used in vaporizins'the more volatile from the'supercharaer for heatins at least part fuels, are not satisfactory because of theinsuf-' of the air mixed with the fuel suppliedto. an ficient velocity oi. the air now therethrcugh. 'The internal combustion ensine. 2 velocity of the air passingby the throat of a; ven- A further object of the present invention is turi tube is dependentfupon the differ n "in; to provide a fuelsupply system for internal compressu'res existingat the inlet and outlet ends 2 bu on enslneswitha control means whe y of the tube. If a Venturi tube beutili zed in either atmospheric air or the hiah Pressure, hilh conjunction with either an engine intake n ani; temperature discharge from the supercharler is fold r with a supercharger, the difference in util n upplvi sfu l to th ena pressures is equal to the diflerencebetween the A further Object of t invention 15 to atmospheric pressure existingst the inlet end; vide control means for a system'of'the type last the suction at the outlet end resulting from the p ifi p m ns t ml l in m to connection or that end to the intake manifold the pressuresener edbv the supercha ser. a or suction sideof the compressor,- n t an: furthermoraa control meanswhich maybereadference inpressures. is .suflicient to produce the dlusted to operate at different DW- 80 air velocity required to vaporize high flash point that when the engine is started or idlint ati'uels, it results in a deoreasein the power out mospheric air is utilized in eifectinl vaporization put of the engine or an extra burden upon the of the fuel. and t 111811 pressure-111811 m supercharger. y y i V ature discharge-is utilized under power opera,- One of the objects of the present invention is of the fl the provision of a new and improved fuel supply "40 Another object of thepresent invention resystem for internal combustion engines; es in providing a combined sup find Another object of the present invention is th carbureter wherein the supercharger comprises p ovisionof a novel combined supercharger a d 'two portions, one for compressing air, alone and carbureter, and ne ad pted t e g y for m n the otherfor compressing a mixture ofair and flash point fuels, 1 r p I fuel, and wherein the supply of fuel for mixture Another object of the invention resides in the i i d the supply air to one utilization of a, portion of the high pressure, hi the compressor are controlled coniointly. V temperature discharge of a supercharger in the. 'A further object of the present inventioni'evaporization oi fuel, and further, in. utilizing air side's inthe provision of new and improved superor a mixture of air and fuel dischargedby the so l s supercharger for this purpose. 1 Another object of the present invention re- 'Ancther and "somewhat more specific object sides in the provisionof a novel method of supof the present invention is to provide; a new and plying a mixture of air and fuel to an internal improved fuel supply system for internal comcombustion engine through a centrimsid p 66 supercharger, which includes the step of heatins mixture of air fuel to the suction side of the supercharler wherein the hizh pressure, high temperature discharae from thesupercharger is utilised to eilectamcre comat least part of the air mixed with the fuel by heat generated by the supercharger and obtained from the discharge side thereof.

Another object of the present invention resides in the provision of a novel method of supplylnu fuel to an internal combustion engine through a centrifugal. type supercharger and a fuel injection device connected to the suction side of the supercharger, which includes passing a portion of the high pressure, high temperature supercharger dischar e through the device.

A still further object of the present invention resides in the provision of a novel method of supplying fuel to an internal combustion enZine through a centrifugal type supercharger and a fuel injection device connected. to the suction side of the supercharger, which includes passing atmospheric air through the device when the engine is idling and passing a portion of the high pressure, high temperature supercharger discharge throughthe device when the engine is operating at a predetermined speed above idling Further objects and advantages of the present invention will become apparent from the ensuing descriptlon, in the course of which referonce is had tothe accompanying drawings in which:

Fig. l is a side elevation illustrating the fuel supply means of the present invention attached to an internal combustion engine:

Fig. 2 is a front elevation of the apparatus showninl 'imlr Fig. 8 is a vertical cross-sectional view through thefuel supplymeans of the present invention;

Fi 4 is a vertical cross-sectional view of ana other embodimentof my invention:

1'18- 5 is a horizontal cross-sectional view 1 through a heat exchanger forming part of the illustrating a form of control for automatically changingover from idling to power operation which may be utilized with any of, the embodiments of the present invention but which is illustrated in less detail in Fig.3;and

Flu. is a horizontal ,crosssectional view taken along the line "-40 of Fig. 9.

The fuel supply means of the, present invention may be ,considered in one aspect as being a combined carbureter and supercharger which may be utilized with various types of, internal combustion engines, but which is particularly designed for utilization in airplane engines operated with a high flash point fuel. In Figs. 1 and 2 the combined carbureter and supercharger, in-

' dicated generally by reference. character It,- is

shown attached to and forming part of an in ternal combustion engine illustrated ciiagiummatically and indicated by reference character It. 'rheengine is supplied with a mixture of compressed'air and fuel through a conventional intake manifold i4 connected to a discharge conduit I, connected, in turn, to the discharge outlet ll of the carbureter and supercharger ll.

Fuel is supplied to the engine from a supply tank (not shown) by an engine-driven fuel pump 20 of the diaphragm type connected to the supply tank by a conduit 22. The discharge side of the pump is connected by a fuel feed line 24 to the combined carbureterand supercharger.

The combined carbureter and supercharger comprises a two-part' 'casing, which may take the form of and which is illustrated as a pair of castings suitably secured together and to the engine, and an impeller 28 (see Figs. 3 and 4) of novel construction rotatably mounted within 'the'casing. The casing and rotor constitute, as

may be noted from the drawings and as will be described in greater detail hereinafter, a compressor of'the centrifugal type.

" The impeller 28 is driven at high speed by suitable gearing contained within an enclosur 30 and interconnecting the engine crankshaft (not shown) with a gear 32 fixedly secured to the impeller shaft 34, as illustrated in Fig. 3.

The impeller shaft is mounted for rotation in a pairof spaced-apart bearing races 28 suitably mounted in recesses 38, one of which is formed in one part of the casing 28 and the other in a bracket formed integrally with that part of the casing. The'bearing races and gear 32 are spaced from each other as well as from an impeller hub. portion 42 by three sleeves 44, and theseelements are secured in spaced-apart relationship by means of a nut 45 secured to the threaded end of the impeller shaft 34.

The compressor constituted by the casing 26 i and the impeller 28 serves not only as a superpreviously mentioned hubportion 42 and a inrality of radial vanes 4', and the other by a hub portion 48 and radial vanes 50. The two sets of vanes are separated from each other by a circular partition 52 formed integrally with the hub 48 and vanes 50. The two impeller portions are suitably afllxed to the impeller shaft 34 as by means of a key 54, and the hub 48 terminates in'a conical end 64 to provide a more eflicient flow of fluid thereby. I

'I'he compressor portion, defined by hub 42 and vanes 46, is utilized to compress the supply of secondary air which is supplied thereto through an annular suction chamber 68 and an airinlet passage Ill. The latter is provided with a valve 42 for a purpose and operated in accordance with a manner to be described more fully hereinafter. The compressed air is discharged into a discharge chamber 64.

The impeller portion constituted by the hub 48 and vanes 50 is utilized to compress a mixture of fuel and air supplied thereto through an annular suction chamber 48, and the compressed mixture is discharged into the discharge chamber 84.

The impeller is made in two portions, one for compressing air and the other for compressing air and-fuel, in order to make the compression of air and fuel substantially independent of the compression of air alone. It is preferred, particularly with extremely high flash point fuels, that the'lmpeller vanes ill of the air and fuel compressing portion be made somewhat greater in diameter than the vanes 46 of the air compressing portion, in order to obtain aflgreater suctionat the suction side of the air and fuel compressor.

As has already been indicated, the fuel supply means of the present inventionis designed particularly for use with fuels having a high flash point. Fuels of this nature, in order to be utilizable, must be vaporized to a high degree. This vaporization may be effected mechanically, by the application of heat, or by use of a carbureting device such as a Venturi tube. According to the present invention, the Venturi tube and mechanical mixing are utilized to effect starting and idling operation of the engine, and

,high velocity; high temperature air or mixture of air and fuel is utilized in addition to these in order to secure a more complete vaporization and, therefore, more efficient operation of the engine at speeds above the idling speed.

orifice 288 or to a conduit 282 communicating Fuel =15 supplied to the combined carbureter and supercharger through the previously mentioned conduit 28 and preferably, but not necessarily, through a pair of series connected fuel injection Venturi tubes of the stepped type indicated'generally by reference characters 18 and I2, the latter of which leads to the suction chamber 88. The tube 18 may be considered as a primary tube and the tube 12 as a secondary tube. The use of series connected Venturi tubes is particularly advantageous in the utilization of. a high flash point fuel inthat a more complete,

mixture of fuel and air as'well as vaporization of the fuel is obtainable because of the higher velocity of the air or mixture of air and fuel flowing through the primary tube,

The supply. of fuel and of secondary air are controlled, respectively, by a needle valve I8 and the previously mentioned valve82 locatedin the air inlet passage 88. The positions of these valves are controlled jointly through a rod 18 extending to the operator's compartment of the vehicle driven by theengine. The rod I8 is con nected by a crank arm 18 operableto rotate a shaft 88, upon which the valve 82, is mounted, and a crank arm 82 connected by a rod 88 to a cam 88 controlling the position of the needle valve 18.

The controlling mechanism, as well as the valves, are indicated in the positions they occupy when the engine is idling. At this time the valve 82 is closed and the needle valve 18 is opened to supply only a limited amount of fuel to the with conduit H8through a flow restricting ori- V fice member 288, dependent upon the position of a, valve 288. The latter is shown in the position it occupies during idling, at which time conduit H2 is connected to theatmosphere through the orifice 288. The valve288 is shifted to close orifice 288 and toplace conduits H2 and H8 in communication at adjustable predetermined compressor discharge pressures. The valve is operated by a bellows 288 closed at its upper end by a movable plate 218 and connected at its lower end by a relatively small diameter conduit 212 to the conduit H8. The conduit 212 extends within the bellows through an. aperture formed in a fixed base plate 218 adiustably mounted on a plurality of supports 218 of which only two are shown. The movable plate 218 is connected to the valve 288 by a lost motion connection including a stud 218 threaded through the plate 218 and hollowed at its upperend to-receive a bolt 288 secured to the valve 288 and biased downwardly by a spring 282- (Fig. 9), held between the head of the bolt and a cap 288 closing the hollow end of the stud 218 (Fig. 9). A bellows type seal 288 serves to prevent leakage of fluid past the stud 218.

When the engine is idling, a pressure less than atmospheric pressure exists within the bellows 288 by reason of the domination of the auction in the intake manifold over the pressure generated by the compressor. Consequently, thebeilows 288 tends to collapse to hold the valve 288 I in the position indicated. When the pressure Venturi tubes. The needle valve is attached at its outer extremity to a cap-like member 88 maintained in engagement with the cam 88 by a spring 88 located therebetween and a circular boss 82 formed at the outer extremity of a structural member 88 which includes the Venturi tube II as an integral part thereof. A bellows 88 is utilized to prevent leakage of fuel from about the needle valve 18, and in orderto permit efllcient operation of the needle valve, the interior of the bellows is connected to the fluid conduit by means of a passage 88.

Fuel is supplied to the firstventuri tube 18 through a passage i82 connecting conduit 28.

and an annular passage I88 from which'a plurality of orifices l88lead to the throat I88 of the Venturi tube. n

One of the important features of the present invention resides in the utilization of a portion of the high pressure and high temperature air or fuel mixture from the discharge side of the supercharger during power operation of the engine to obtain a thorough vaporization of the fuel and in the utilization of atmospheric air when the engine is idling.

The conduit H2 is adapted selectivelyto be connected either to the atmosphere through an generated by the compressor increases, the bellows tends to expand and to move the valve op-' a small quantity of oil may be placed in the cupshaped member 288, as indicated in Fig. 9.

To provide an arrangement whereby the pressure at which the valve 288 is moved upwardly may be varied, the engaging surfaces may be so constructed and arranged that the contact area therebetween may bevarie'dt A simple arrangement for doing this is illustrated more particularly. in Fig. 10 from which it may be seen that the member 288 may be rotated a small amount upon loosening of a pair of screws 288 by means of which the member is secured to the plate 218. The contacting surfaces of members 288 and 288 are cut away, as indicated at 288, so that the contact area therebetween may be varied by rotating one member relative to the other.

The adjustment of the amount of flow of air or of air and fuel through the conduit H8 and through the Venturi tubes may be effected by utilizing orifice members 288 of different sizes. These orifice members are removabiy mounted in arecess 888 formed at the end of conduit 282 so that it is a relatively simple matter to substitute one orifice member for another.

When the engine is idling, the suction created created by the flow of air past the orifices Hi6 and of the pressure applied by the fuel pump to the fuel, vaporized fuel is supplied to the outlet 7 end I28 of the Venturi tube ID, the outer end of l which is closed by a cap I30. The outlet end of conduit I and a heat exchanger indicated as.

a whole by reference character I46. When the engine isidling,the suction created by the compressor and in the intake manifold is eflective alsotodraw in atmospheric air through the Venturi tube 12. The air which flows past the throat I" of the Venturi tube I2 is effective to draw in the, mixture of air and fuel from the first Venturi tube Ill and further vaporize the fuel so that a mixture of substantially completely vaporized fuel and air is suppliedto the suction chamber 86 and, thus, to the intake manifold through the supercharger and conduit It.

The Venturi tubes are so designed that the fuel supplied to the intake manifold is vaporizedsufflciently to at least enable the engine to start and idle. At this time the vaporization of the fuel is effected by the two Venturi tubes and by the mechanical action of one portion of the compressor, that is, the portion comprising the vanes ll. Under idling conditions the engine does not rotate at a very high speed, and consequently the mixture of air and fuel is not compressed to an appreciable extent. The temperature of the mixtherefore, is not particularly high and the heat exchanger I" does not appreciably raise.

the temperature of the atmospheric air. How-. ever, under power operation of the engine, the temperature of the atmospheric air is raised to an appreciable extent to increase the vaporization of the fuel. The vaporization is also increased by the connection of the inlet end of the first Venturl tube to the compressor discharge chamber '4 through conduits H2 and Hi. It maybe seen, therefore, that vaporization of the fuel is assisted by the heat of compression and power losses in the supercharger.

The heat exchanger I46, illustrated best in Figs. 4 and 5, comprises a number of flattened tubes I50 secured to and extending through a conduit I52 interconnecting conduit l8 and the compressor outlet port It. The air passing through the several tubes I50 is heated by the compressedmixture of fuel and air flowing around the tubes through the conduit 152 to the intake manifold.

Under power operation of the vehicle, the supercharger is driven at a considerably higher rate of speed, with the result that the pressure existing in the discharge chamber rises to a predetermined value, dependent upon the characteristics of the engine and fuel, sufllcient to open the valve 288 through the influence of bellows 288 into which the pressure is now conducted through conduit 21!. when the valve moves upwardly, it is effective to close orifice 260, to cut off the supply of atmospheric air to the first Venturi tube, and to substitute the high pressure, high temperature mixture of air and fuel obtained from the discharge chamber 84 in place thereof, with the asssjna result that the. vaporization of the fuel is in-' creased by reason of the higher velocity and temperature of the mixture with which it is mixed in the Venturi tubes and supercharger.

In operation, the impeller of the compressor is rotated at a speed proportional to that ofthe engine. When the engine is idling, it is supplied with a limited amount of fuel by the fuel pump and the combined carbureter and supercharger of the present invention. At this time the air inlet butterfly valve 62 is closed and the needle valve" is open only a limited extent. The change-over valve 266 is at its lowermost position so that the orifice 260 is open and the conduit I is leading to the discharge chamber is closed. Fuel is supplied to the intake manifold as a result of the suction in the intake manifold and that created by the slow speed operation of the compressor and the resultant flow of atmospheric, air through both the Venturi tubes. The air drawn through the first of the Venturi tubesp rti lly v porlzes the fuel, and the air drawn through the second Venturi tube 12 is effective further to vaporize the fuel. The fuel is furthervaporized by the supercharger and then flows to the intake manifold. TheVenturi tubes are so designed that at this time the fuel is vaporized sufficiently to permit the starting and idling of the engine even be of a type having a high flash point. j

The anterior throttle valve 82 of the supercharger and needle valve II are mechanically interconnected and the needle valve is so shaped that the proper amount of fuel will be delivered to the intake manifold of the engine when the engine is operated at speeds above the idling speed. Upon the operation of the control mechanism to supply an added amount of fuel to the engine, the supercharger inlet valve and the fuel valve I4 are both opened, and as the pressur in the compressor discharge chamber 64 increases above a predetermined value, the valve 268 is moved upwardly to open conduit H8 and close oriflce 260. A small portion of the high temperature, high pressuremixture of air and fuel in the'discharge chamber 84 is thus caused to flow through the first Venturl tube III more effectively to vaporize the fuel supplied to the second Venturi tube II. The atmospheric air, flowing through the second Venturi tube, which is at this time heated by the mixture of air and fuel flowing from the supercharger to the intake manifold, is also more effective in vaporization of the fuel flowing to the supercharger. The increased speed of rotation of the impeller also results in an increased mechanical action upon the mixture of fuel and air so that the fuel supply means as a whole is effective substantially completely to vaporize even a very high flash point fuel, the use of which is highly desirable in airplanes because it cannot be ignited by incendiary bullets and does not burn if spread over the wreakage of a crashed airplane and which may be obtained at a fraction of the cost of fuels now commonly utilized in airplanes.

The utilization of the heat of compression and 'powerflosses of the supercharger for preheating I ization of the fuel. If-an external source of heat were utilized to vaporize the, fueL'then the heat thus applied would be effective to increase the temperature of the mixture supplied to the intake manifold above the temperature to which it is raised by the supercharger alone, and there by decrease the weight of the charge supplied to each engine cylinder. Accordingto the instant invention and as pointed out above, an increased vaporization is obtained without any increase in the temperature of the mixture-supplied to the intake manifold of the engine.

While the embodiment of the invention dewould be preferable to connect the outlet end of Venturi tube 18 directly to the suction side of the compressor.

In the practice of the present invention it is not necessary to utilize [a heat exchanger or to utilize a supercharger constructed in accordance with the details outlined above. For instance the impeller may be made in two sections separated by a fixed plate, and compressed air alone, instead of a mixture of gas and air,

may be utilized during power operation of the engine to provide a morecomplete vaporization and. atomization of the fuel. A construction of this nature has been illustrated in Figs. 6 and '1 wherein parts like those of the previously described embodlmentare indicated by like reference characters. I V

The compressor of this embodiment comprises a casing made of two castings I82 and I84, separated by a fixed plate I88 having a shape such as that illustrated more particularly in Fig. 7. The impeller shaft has mounted thereon a hub I88 to which is secured a plurality of radial vanes I18 rotatable in the space defined by casting I62 and plate I88, and a plurality of vanes I12, of a diameter greater than vanes I18, rotatable in the space defined by the casting I84 and plate I88. The air inlet passage 80 leads to the annular suction chamber 88 and the compressed air flows into an air discharge chamber I14, and the latter is open to the compressor outlet port I8 connected to the conduit I8 leading to the intake manifold I4. The air discharge chamber I14 communicates with a conduit I18 which is closed by the valve I22 when the engine idles. The valve'l22 lsweighted and is operable to open the conduit and close the orifice Ill when the pressure generated by the compressor is above a predetermined value. A conduit II2 connects either the orifice or the conduit I18 to the first Venturi tube III which is substantially the same in construction astheflrst Venturi tube of the previously described embodiment. In the instant embodiment, fuel is supplied to the combined carfuel compressor portion of the supercharger. This compressor discharges into a discharge chamber I88 which, like the air discharge chamber I14, is open to the outlet port l8, as best illustrated in Fig. 7A. I i

The operation of the embodiment of Figs. 6 and? is substantially the same as that of the previously described embodiment, except that the air supplied to the second Venturi tube I82is not heated and in that air alone passes through the conduit II2 both during idling andpower operation of the engine. Air alone is compressed by one compressor section and a mixture of fuel and air by the other, and the compressed air and compressed mixture are thoroughly mixed to gether in the discharge conduit I8 prior to being supplied to the intake manifoldof the engine. Inasmuch as air alone is supplied to the first Venturi tube, vaporization of fuel by the latter is increased. I

The embodiment of Fig. 8 is similar to that of Figs. 6 and rm so far as mode of operation is concerned, differing therefrom primarily in structural details. The compressor of this embodiment comprises a pair of castings 288 and 282 within which is mounted an impeller, indicated generally by reference characterfll. The impeller is fixedly. secured to the impeller shaft 88. Air is supplied to the compressor through an inlet conduit 288 formed integrally with the casting 282 and opening into an annular suction chamber 288. The suction chamber communicates with a plurality of axially and radially extending passages 2" formed withinthe impeller and constituting the air compressing portion of the compressor. The impeller is also provided with a plurality of axially and radially extending passages 2I2 communicating with radially extending passages 218 which together constitute the fuel and air mixture compressing portion of the impeller. The passages 2" and 2 open into the compressor discharge chamber 2I8 at the same distance from the axis of rotation, and the chamber, in turn, communicates with the compressor outlet port I8;

Fuel is supplied to the supercharger through a pair of series connected fuel injection Venturi tubes 2l8 and228, the latter of which extends I into an axial circular recess 222 in the impeller with which the impeller pasageways 2I2 communicate. As in the-previously described embureter and supercharger through-the fuel feed line 24 under the control of a needle valve I4 controlling the eflective size of an orifice 222 leading from the fuel line to an annular chamber 228 connected, in turn, by a plurality of orifices 226 to the throat 228 of the Venturi tube 2.

The Venturi tube 2I8 is preferably formed as a sleeve adapted to be inserted into a recess formed in the compressor casing casting 282. i The needle valve I8 is also slidably mounted in a boss formed asan integral part of the same casting. When the engine is idling, the inlet end288 of the first Venturi tube H8 is connected to the atmosphere through an elbow conduit 282 and an orifice 288 5 formed at the upper end of the other compressor substance, a suction chamber forthe air and 1s .cas'ingcasting 288. When the engine is driven at higher speeds and the pressure generated by the compressor rises above a predetermined value. the inlet end 288 of the Venturi tube 2" is. 00D: nected to the compressor discharge chamber 2I8 through a port 288. the valve 288 being moved upwardly to close the orifice and open the port by "the pressure generated by the compressor. The

valve 2:: is provided with a stem m slidably mounted in a guiding member 242 formed at the upper end of the casting 200.

The air and fuel flowing past the throat of the first Venturi tube flows to the second Venturi tube 220 through the outlet end 2 of the first Venturi tube, a port 246, an annular chamber 2, and a plurality of, orifices 250 leading from the annular chamber to the throat 252 of the second Venturi tube. The inlet end 254 of the second Venturi tube is open to atmosphere and the outlet end 256 thereof leads to the recess 222 in the impeller.

The fuel valve 14 and air inlet valve 82 are connected for conioint control by the operator by mechanism substantially the same as that previously described and indicated by the same reference characters. v

The last described embodiment of the present invention is similar in somerespects to the two first described embodiments. It is similar to the firstin that a mixture of air and gas is utilized during power operation of the vehicle to effect vaporization of the fuel, and similar to the second described embodiment in that the air supplied to the second Venturi tube is not preheated. One advantage of the lastdescribed embodiment results from the fact that the closed passage impeller does not require the accurate clearance therebetween and'the compressor casing required by the previously described embodiments. I

In the adaptation of the fuel supply means described above to various types of airplanes or for use of different types of fuels, it may be desirable to vary the fiow of air or the mixture of air and fuel from the discharge chamber of the compressor through the Venturi tubes, or it may be desirable to change the pressure atv which the change-over valve is operated to supply the high temperature compressed air or mixture of gas and air to the Venturi tubes. The type of valve operating mechanism shown in eitherFig. 3 or Fig. 6 may be used.

From the foregoing description of several embodiments of the present invention, it may be noted that the invention is susceptible of considerable modification by those skilled in the art. For instance, many of the desirable results of the invention mayv be realized with fuel injection devices other than Venturi tubes. It should be understood, therefore, that the described embodi- 'a liquid fuel injection Venturl tube for supplying a mixture of air and fuel to the second of said compressors, and conduit means conducting fluid under pressure greater than atmosphere from the discharge chamber of the first compressor to the inlet end of said Venturi tube.

2. In a fuel supply system for an internal combustion engine, the combination including, a liquid fuel injection Venturl tube having inlet and outlet ends, a centrifugal compressor having a suction chamber communicating with the outlet end of said tube, a second suction chamber communicating with the atmosphere and separate impeller elements and discharge chambers associated with said suction chambers to define air and fuel compressors, conduit means connecting said discharge chambers to the engine, and conduit means connecting the air discharge chamber to the inlet end of said Venturi tube for supplying all of the fluid to the inlet end of said Venturi tube, when the compressor delivery pressure is high.

3. In a fuel supply system for internal combustion engines, the combination includin a supercharger for supporting fuel under pressure to the engine, means including a fuel injection Venturi tube having an outlet end continuously communicating with the suction side of said supercharger for supplying fuel to the latter, and means including a device responsive to the pressure generated by said supercharger for selectively connecting the inlet end of said tube to atmosphere or to the discharge side of said supercharger.

4. In a fuel supply system for internal combustion engines, the combination including, a supercharger for supplying fuel under pressure to the intake manifold of the engine, means including a fuel iniection Venturi tube having an outlet end communicating with the suction side of the supercharger for supplying fuel to the latter, conduit means adapted to connect the inlet end of said tube to atmosphere, conduit means adapted to, connect the inlet-end of said tube to the discharge side of "said supercharger, a two position valve normally opening said first conduit means and closing the second conduit means, and means operable in response to the pressure generated by the supercharger for operating said valve, said last mentioned means including a bellows connected by a conduit of restricted cross-sectional area tothe discharge side of said supercharger, and a pair of surfaces in close contact with each other for preventing the bellows from operating the valve until the pressure generated by the supercharger exceeds a predetermined value above atmospheric pressure.

5. A system as claimed in the preceding claim, wherein the surfaces are rotatable with respect to each other-to vary the contact area therebetween, thereby to vary the. pressure at which the valve is operated.

6. In apparatus of the class described, the combination including, a supercharger for supplying fuel under pressure to an engine, and means for supplying fuel to the supercharger, said last mentioned means including a pair of fuel injection Venturi tubes connected in series, means for supplying fuel to the throat of the first of said tubes, the inlet end of the first of said tubes being in communication with the high pressure side of said supercharger, the inlet end of the second of said tubes being in communication with the atmosphere, the outlet end of the second tube being in communication with the suction side of the supercharger, and means for heating the atmospheric air flowing to the inlet of the second tube by heat derived from the discharge side of the supercharger.

7. In apparatus of the class described, the combination including, a supercharger for supplying fuel under pressure to an engine, said supercharger including an air inlet conduit and a fuel inlet, means for supplying fuel to said fuel inlet, said means including a pair of fuel in- Jection Venturi tubes connected in series, a variable position valve for controlling the flow of ofthe first of said connecting the inlet end fuel to the throat of the first of said Venturi tubes, said valve having an idling position in which only a limited amount of fuel is supplied to said Venturi tube, conduit means for connectingthe inlet end of the first of said Venturi tubes to atmosphere, conduit means-for connect- ;ing the inlet end .of the first of said Venturi tubes to the high pressure side of said supercharger, valve means for normally openingthe first of said conduit meansand normally closing a the second of said conduitineans, the inlet end of the second of said Venturi tubes being connected to atmosphere and the outlet end thereof being connected to said fuel inlet, a valve in said-air inleteonduit for controlling thefiow of air 'therethrough, said valve having an idling position-wherein thesfiow of air through said saidvalve means to open said normally closed conduit means and toclose said normally open conduit means when the pressure in the high pressure side of thesuperchargerrises abovea predetermined value in the power operation of theengine.

a. In" apparatus of the "ma -as essed, the

combination including, a supercharger comprising apair of compressors, onefor. compressing air and the seccndfor compressing a mixture of air and fuel; andboth discharging into a com-t mon discharge chamber for supplying fuel to an engine, means for supplyingvair to thesuction side of the first of said compressors, and means for supplying a mixtureof air and fuel tothe suction sidewof the second of said compressors,

said last mentioned means including apair of fuelinjection Venturi tubes; connected in series,

means for supplying liquid fuel to the throat or the first of said Venturi tubes, conduit means for connecting the inlet end of the first Venturi tube conduit is substantially cut oil, means for simul taneously opening both of said'valvesfor power operation of the engine, and means for operating to the, pressure in the opening the "first and idling speed for controlling the supply of air to the throat of the combination including, a supercharger comprising a pair, of compressors, one for compressing air and the second for compressing a mixture, of air and fuel, and both discharging into a common discharge chamber for supplying fuel to an engine, means including a suction chamber and an air inlet conduit for supplying air to the suction side of the first of saidcompressors, means for'supplying a mixture of air and fuel to the suction sideof the second of said compressors,

said last mentioned means including a pairof fuel injection Venturi tubes connected in series, means connectingthe outlet endofthe second Venturi tube to the second of said suction chambers,=means connecting the inlet end of the second Venturi tube-to atmosphere, conduit means for connecting the inlet end eithe -first Venturi tube to said discharge chambe conduit means for connecting the inlet end of saidfirst ,Venturi tube to atmosphere, valve means normally closing the first and opening the'second of'saidconduit means and operable in response discharge chamber for closing the second, a valve that is closed when the engine is operating at flowing through the air inlet conduit, a variable position valve firstv of said Venturi tubes,

said valve admitting but a limited supply of fuel to said Venturi tube when the engineis idling,

a and control means operable simultaneously to open both of saidvalves.

to said discharge chamber, conduit means for connecting the inlet end of ithesecond Venturi tube to atmosphere at atmospheric pressure, and Vmeans connecting the outlet end of the "second Venturi tube with the second of said suction chambers. i

therewith, saidcasing including a single chamber 9. In apparatus of the class d escribed, thecom- 'bination'including, a supercharger comprising a pair of compressorsyone for compressing air andthe second for compressing a mixture of air r and fuel, and both discharging into a-common discharge chamber. for supplying fuel to an engine, meansfor supplying air to the suctionside compressors, means-for supplying a mixtureof air'and fuel tothe suction side of the second of said compressors, said last mentioned means including ;a pair of fuel in- ,iection Venturi tubes connected inseries, means for supplying liquid fuel to the throatlof the,

first of said, Venturi tubes, conduit means i, for

connecting theinlet end of the first Venturi tube to said discharge chamber, conduitumeansfor of said first Venturi tube to atmosphere, valve means normally .closing the first of said conduit means and opening the second and operable in response to the pressure in thedischarge' chamber for opening the first and closingthe second conduit means, means connecting th'e'inlet end of the second Venturi tube to atmosphere at atmospheric pressure,

Venturi tube to the second of said suction chambers.

10. In apparatus of the class described, the

and means connecting the outlet end of the second into which both portions of the impeller discharge, one of said casingpartsbeing formed with a radialreces opening into the suction chamber in 'said casing part, a

series with the first mentioned Venturi tube, and conduit defining means for. connecting the inlet end of the second Venturi, tube to the discharge chamber of the compressor.

12. A combined carbureter and'supercharger for use with internal combustion engines, including in combination, a compressor casing compriseach of which has. formed integrally therewith an annular suction chamber,

an impeller mounted within said casing for rotacompressor portions separated by said casing parts being opening into the formed with a radial recess opening tion chamber in said casing part.

tion aboutan axis co-axial with respect to the suction chambers, saidimpeller comprising two a circular plate,

- said casing including a single chamber into which both portions of the impeller discharge, one of suction chamber formed in said other of said casing parts being casing part, the

' into the sue tion Venturi tube mounted in said recess, a sec- -ond,fuel injection Venturi tube comprising a separate structural element secured to said calforcontrolling the supply of fuel' fuel injection "Venturi'tubemounted in said recess, a second fuel injection Venturi tube comprising a separate 7 structural element secured to said casing and I connected in formed with an air inlet a fuel injec- 'charge' chamber reaches a foro'pening said conduit and closing said orifice, Venturi tube to the conduit discharge chamber in such manner that when the valve is in its normal position said conduit is ing and connected in. series withthe first mentioned Venturi tube, a conduit in communication -with the discharge chamber of the compressor and having an orifice open to the atmosphere, a valve biased to closesaid conduit and to open said orifice and operable to open said conduit and close saidorifice'when the pressure generated by the compressorreaches a predetermined value,

and a conduit connecting the inlet end of the second Venturi tube to said last mentioned conduit in such mannerthat it is normally in communication" with the atmosphere through said orifice. Y

13. A combined carbureter and supercharger: -ior use with internal combustion engines, including in combination, a compressor casing comprising" two parts, each of which has formed integrally therewith a suction chamber and a discharge chamber, a two-part impeller rotatably.

mounted within said casing, a partition between the two parts of the casing and the two portions of said impeller, a common outlet port forboth discharge chambers, a fuel injection Venturi tube formed integrally with one part of said cas- 11 8183131 tube having its outlet end opening into the suction chamber formed in said casing part,

' a second fuel injection Venturi tube comprising a separate structural element discharging into the constricted partof the Venturi tube forming a portion of said one of the casing parts, and

conduit forming means connecting the inletend of the second Venturi tube to the air discharge chamber of the compressor. V I

' 414. A'combined carbureter and supercharger for use with internal combustion'engines, including in combination, a compressor casing comprising two parts each of which has formed integrally therewith a suction chamber and a discharge chamber, a two-part impeller rotatably mounted within saidcasing, a'partition between I the two parts of the casing and the two portions of said impeller, a common outlet port ior both discharge chambers, an air inlet conduit formed integrally with one of said casing parts and communicatingwith the suction chamber formed in said part, a fuel injection Venturi tube-formed integrally with the other casingpart, said tube having its outlet end opening into the suctionv chamber formed in said casing part, a second fuei injection Venturi tube comprising a separate structural element secured to the Venturi tube defining portion of said other casing part, a conduit leading from the air discharge chamber and formed integrally with said one casing part, said conduit terminating in an orifice open to the atmosphere, a valve normally closing said conduit and operable when the pressure inthe air disa' conduit connecting the inlet end of the second leading from the air connected to atmosphere through said orifice,

and whensaid valve is operated to close the orifice, it is connected tothe, conduit normally I closed by the valve.

predetermined value,

provided with a central recess and an annular discharge chamber the other of said casing parts being provided with an annular suction chamber and an air inlet leading thereto, an impeller rotatably mountedbetween said casing parts, said impeller having an axial recess and a plurality of passages leading therefrom to the outer periphery of the impeller, a fuel injection Venturi tube having its outlet end extending into said recessand supported by the other of said casing parts, said impeller also having a plurality of axially and radially extending passages, the axial ends oi which open into said suction chamher and the outerends of which open into said discharge chamber, a radial recess formed in the other of said casing parts, the axial end of said recess being in communication with the throat of said first Venturi tube, a second fuel injection Venturi tube mounted in said recess with its outlet end located nearest the axis, a

'valve chamber having an orifice open to atmosphereat its upper end formed in said one of the casing parts, a port connecting said chamber to i said'annular discharge chamber, a valve mounted in said valve chamber normally closing the port and operable to open the latter and close said orifice when the pressure in the discharge chamber reaches a predetermined value, and

conduitimeans for connecting said valve chamber'to the inlet end of the second of said Venturi tubes. s

'16. In combination with-an engine intake, a combined carbureter and supercharger structure, a casing of said structure having a divided impeller therein and having. two high and two low pressure-chambers externally and internally respectively of respective divisions of said im 'peller, one internal chamber and its associated external chamber conducting air only to-said engine intake, the other internal chamber and its air and the second for compressing a mixture of air and tueL-and both discharging into a commondischarge chamber for supplying fuel to an engine, means for supplying air tothe suctionside of the first of said compressors, and

. means for supplying a-mixture of-airand fuel 15. A supercharger for use'with internal com- 'bustion engines,

including in combination, a two-part casing,

one of said casing parts being I exchanger located in the to the suction side of'the second of said compressors, said last mentioned means including a pair of fuel injection Venturi tubes connected in series,umeans for supplying liquid fuel to the throat of the first of said Venturi tubes, conduit -means for connecting the inlet end of the first Venturi tubeto'said discharge chamber, conduit meansi'or connecting the inlet end of the second Venturi tube to atmosphere througha heat path of the discharge from the supercharger, andv means connecting the outlet end of the second Venturi tube with .the secondoi' said suction chambers.

' AUGUSTUS e. DURDIN, JR. 

